What is the recommended dosing of prazosin (Prazosin) for patients (pts) with post-traumatic stress disorder (PTSD)?

Prazosin Dosing for PTSD

For patients with PTSD-associated nightmares, prazosin should be initiated at 1 mg at bedtime and gradually titrated by 1-2 mg every 3-7 days until effective, with typical maintenance doses ranging from 3-15 mg daily depending on patient population (lower doses for civilians, higher doses for veterans). 1

Initial Dosing and Titration

• Starting dose: 1 mg at bedtime 2, 1
• Titration schedule: Increase by 1-2 mg every 3-7 days based on response and tolerability 1
• Monitoring: Check blood pressure after first dose and during dose increases to monitor for orthostatic hypotension 1

Population-Specific Dosing Considerations

Military Veterans

• Typical effective dose range: 9.5-15.6 mg/day 2, 1
• Maximum studied dose: Up to 20 mg daily in divided doses 3
• Some veterans may require higher doses (up to 15-20 mg) for adequate symptom control 2

Civilian Trauma Survivors

• Typical effective dose range: 3-6 mg/day 1
• Mean effective dose in civilian studies: 3.1 mg ± 1.3 mg 2

Gender Differences

• Women may respond to lower doses (average 7.0 mg) compared to men (average 15.6 mg) 2, 1

Dosing Schedule Options

1. Standard approach: Once daily dosing at bedtime for nightmare-predominant symptoms 2
2. Divided dosing: For patients with both nightmares and daytime symptoms:
   • Consider twice or three times daily dosing 4
   • Morning dose may help with daytime flashbacks 4

Monitoring for Efficacy

• Evaluate nightmare frequency and intensity after 2-4 weeks at each dose level
• Use standardized measures like CAPS "recurrent distressing dreams" item 1
• Target is ≥50% reduction in nightmare frequency/intensity 2

Side Effect Management

• Primary concern: Orthostatic hypotension, especially during initiation and dose increases 1
• Common side effects: Dizziness, drowsiness, headache 1, 5
• First-dose effect: Consider administering initial dose at bedtime to minimize orthostatic symptoms 5
• Caution with concurrent PDE-5 inhibitors due to additive hypotensive effects 3

Treatment Algorithm

1. Initial phase: Start with 1 mg at bedtime
2. Titration phase: Increase by 1-2 mg every 3-7 days
3. Target dose:
   • Civilians: 3-6 mg/day
   • Veterans: 9-15 mg/day
4. Inadequate response: If partial response after 4-6 weeks at maximum tolerated dose:
   • Consider further dose increases up to 20 mg daily (some case reports show benefit up to 30-45 mg in treatment-resistant cases) 6
   • Consider adding adjunctive therapy (e.g., Image Rehearsal Therapy) 1

Important Clinical Considerations

• Prazosin has Level A evidence for PTSD-associated nightmares 2, 1
• Response may occur within 1-2 weeks of reaching effective dose 5
• Patients taking SSRIs may show decreased response to prazosin 2
• Some patients may require long-term maintenance therapy, as symptoms often return upon discontinuation 2, 7

Prazosin offers a well-tolerated and effective approach for managing PTSD-related nightmares, with strong evidence supporting its use as first-line pharmacotherapy for this specific symptom.